Robert Sawyer has again given writers some advice. Usually, I think his advice is reasonably good. This time around, I'm (sort of) not so sure. He basically is advising would-be writers to write a bunch of short stories before they submit. It looks to me as if he is basically drawing from the arc of his own career here. Like a lot of science fiction writers, he started out writing short stories. But not all writers of SF(or any other fiction) start out that way. Because not everybody can write short stories well. I might be able to, but I write "big". I always have. I tackle big, complex stories, and while I can pare down, I find it very hard to pare down to the miniature quality required of the average short story.
Mind you, I used to read a lot of SF short stories. I cut my teeth on science fiction this way, and I absorbed the work of some excellent authors. Robert Heinlein, Isaac Asimov, and Ray Bradbury come immediately to mind. But I also remember, even as a relatively young girl, reading Alfred Bester's The Stars My Destination ---- which is a novel-length work, though very strange in some parts. It's science fiction, after all.
But following his advice, even to get the interest of an agent, probably wouldn't work for me. As I said, I write too "big". Whenever I've wanted to write, it's always been conceived as novel length. I agree with Sawyer that it's much harder, if you're unknown, to interest an agent this way, or a publisher, but there are a lot of things in the publishing world that seem to be changing, some for the benefit of writers, some not. And it would probably not work for the writers I know or am in contact with, most of whom are not yet published, but have good, imaginative works that simply need some polishing.
I think Sawyer is still mentally living in an age when you were pretty much required to "come up" the way he suggests. He still thinks this is the path to getting published. Perhaps he's right. And if you can conceive of "miniature" story arcs, and have the discipline to polish your craft this way, there's nothing wrong with writing short story-sized SF. There are markets for it, and it will get your name in print. But not everybody conceives their story arcs this way, not everybody is attracted to small, spare incidents. And it definitely would not work for, say, a romance writer! Probably not for someone writing mysteries, either. There was a time when this career ladder worked for at least some writers, but you practically have to go back to the days of Fitzgerald and Hemingway to get to that time. Nowadays, yes, there's a lot of work trying to get yourself published, and even then, that won't guarantee success. I read somewhere, that J.K. Rowling got rejected some 25 times before she sold her first Harry Potter book, and after that it got really good "buzz". She was lucky. And she is a very good writer. But she didn't have Robert Sawyer to tell her what she "should" be doing. If she had, Harry Potter probably would not have become the phenomenon it did.